Brake



W. J. RYAN Feb. 6, 1940 BRAKE Filed Jan. 11. 1937 5 Sheets-Sheet 1 2. wa 8 t 2 a L: m a O 2 r 2 2 2 .w a I 1 INVENTOR \IVILLIHM J Rrmv ATTRNEYFeb. 6, 1940. I w J, RYAN 2,189,226

BRAKE Filed Jan. l1, 1937 5 Sheets-Sheet 2 INVENTOR WILLIHM J. RYHN BY350 354 I ATTRNEY w. J. RYAN Feb. 6, 1940- BRAKE Filed Jan- 1937 5Sheets-Sheet 5 INVENTOR \I V ILLIHM d- RYHN ATTORN EY Feb. 6, 1940. I

w. J. RYAN BRAKE Filed Jan. 11, 1937 o W\) 7 llll/l INVENTOR WILLIHM d..RYHN

BY ATTORNEY 5 Sheets-Sheet 4 Feb. 6, 1940. w J, RYAN 2,189,226

BRAKE 0 Filed Jan. 11, 1937 5 Sheets-Sheet 5 INVENTOR ATTORNEY PatentedFeb. 6, 1940 UNITED STATES PATENT OFFICE 2.18am mun a corporation of InApplication January 11, 1937, Serial No. 119,927

19 Claims.

This invention relates to brakes and is illustrated as embodied ininternal expanding shoe brakes for automobiles.

One of the objects of this invention is to provide simple and effectivemeans for adjusting brakes to compensate for shoe wear. In illustratingmy invention I have shown means for adjusting the return position of theshoes so that the clearance between the shoes and the drums ismaintained constant. I have provided means for automatically making thisadjustment so that the constant clearance is automatically maintained. Ihave also provided means for lengthening the effective lengths of theshoes, in combination with means for adjusting the return position, sothat not only is the proper clearance maintained, but also adjustment iseflectively made to the applying means.

According to a very important feature of this invention theseadjustments are preferably made with relation to the braking surface ofthe drum, so that they are not affected by expansion and contraction ofthe drum due to heat and pressure.

A further object of my invention is the provision, in combination withbrakes of the character discussed above and having adjustments such asthose discussed above, of means for preventing the over-adjustment ofthe brakes from other causes than shoe wear, such as for instanceexpansion of the drum due to heat. As one effective means of controllingthe adjustment, I have shown in several embodiments a drum contactmember which is operated by movement of the shoe toward drum contactwhen the shoe is worn to operate an automatic adjustment for the brake.

A further object of the invention is the provision in a servo brake ofthe type which shifts its anchorage in forward and reverse braking, ofmeans for distributing more uniformly the braking pressures on theprimary and secondary shoes of said brake. To this end, the anchoringtorque of the primary shoe in forward braking may be 45 transmitted tothe secondary shoe as an applying force with decreased force, and theanchoring torque of the secondary shoe in reversed braking transmittedas an applying force to the primary shoe with decreased power. Thus thebraking 50 force of the two shoes is more nearly equalized, betterbraking may be obtained and longer life of the brake as a whole ispossible.

A further object is the provision, in an arrangement such as that justdiscussed, of means 55 for automatically adjusting such a brake tocomwith a pair of levers one of which is pivoted on pensate for liningwear and of means for preventing over-adjustment when the drum expandsdue to heat.

One feature of the invention is the provision of drum contact memberswhich cooperate with 5 return stops so asto maintain a constantclearance between the shoes and the drum. A further feature of theinvention is the provision of cams of such design and shape asefliciently to accomplish the desired purposes. 10

A further feature of the invention relates to a cam formed with teethand provided with a spring so arranged that the spring forms the doublefunction of tending to turn the cam and at the same time holds the camin teeth-engaging 14 position so as to prevent the turning of the camexcept when the teeth are disengaged by some other means.

A further feature of the invention has to do the other and so arrangedas to transmit anchoring torque as a lesser force from one shoe toanother so as to apply both shoes more uniformly.

Further features and objects of the invention will be apparent from areading of the subjoined 25 specification and claims and from aconsideration of the accompanying drawings, in which:

Figure 1 is a view in vertical section, just inside the head of thebrake drum, of a brake constructed according .to one embodiment of the30 invention;

Figure 2 is a fragmentary view in section corresponding to a portion ofFigure 1 and illustrating another embodiment of my invention;

Figure 3 is a view in section corresponding somewhat to Figure 1 showinga brake of the servo type which is constructed according to anotherembodiment of my invention;

Figure 4 is a fragmentary sectional view corresponding to a portion ofFigure 3 and showing another embodiment of my invention;

Figures 5 and 6 are also fragmentary views similar to Figure 4 andshowing additional embodiments of servo brakes arranged to act quitesimilar to the embodiment shown in Figure 5;

Figure 7 is a fragmentary sectional view corresponding to a portion ofFigure 3 and also showing another form of servo brake asanotherembodiment of my invention;

Figure 8 is a fragmentary sectional view of another brake illustratingmy invention, being of the servo type and functioning similarly to theembodiment shown in Figure 7;

Figures 9, 10, and 11 are sectional views of brakes illustrating furtherembodiments of my invention, these arrangements being designed for useon brakes of the same general type as shown in Figure l, but also beingfitted for use on servo brakes of the type shown in Figure'3;

Figure 12 is a fragmentary sectional view of a brake illustrating myinvention as applied to a brake of theservo type shown in Figure 3,having means for reducing the force of the anchoring torque used asapplying force for the secondary shoe;

Figure -13 is a sectional view similar to Figure 12 showing a slightmodification thereof; and

Figure 14 is a fragmentary sectional view of a brake similar to thebrake shown in Figures 12 and 13 but provided with a drum contact memberto prevent over-adjustment.

Referring in detail to the drawings, it may be seen that I have shown inFigure 1 a brake drum I0 arranged to cooperate with brake shoes I2 andI4 mounted by means of anchor pins I6 and I8 on a backing plate 20. Ahydraulic wheel cylinder actuator 22 is provided for moving the shoesinto drum contact. Cooperating with the shoes I2 and I4 are return stops24, with each of which a slidable bar 26 is arranged to contact in thereleased position of the brake to maintain the proper clearance betweenthe shoes and the brake. Each bar 26 is arranged to slide in a guidewayformed by lugs 28, 30, and 32 secured to its associated shoe. If it isnot desired to rely on the friction of the ports to hold the bar 26, itmay be provided with means such as teeth 34 which cooperate with a pawl36 or the like urged against said teeth by a spring 38.

It will be seen that when brake-applying pressure is relieved from theactuator 22 the spring 25 will return the shoes I2 and I4 from drumcontact. The amount of the return will be governed by the contact of thebars 26 with the stops 24. So long as there is no wear on the lining ofthe shoes I2 and I4, the pawls 36 hold the bars 26 in the same positionsrelative to its associated shoes, inasmuch as the bars 26 contact thedrum at the same time as the shoes. However, when the lining of eithershoe wears, the'outer end of its bar 26 contacts the drum before thelining does and the bar 26 is moved inward so that the pawl 36 engagesanother tooth. Thereafter, when the brake is released, the inner end ofthe bar 26 contacts the stop 24 before the associated shoe has movedinward as far and the same relative clearance is maintained.

Referring to Figure 2, it will be seen that the bar I26, instead ofbeing arranged to slide radially, is arranged to slide substantiallyalong a chord of the brake drum within guides I28, I30 and I32. Thus theteeth I 34 cooperate with the pawl I36 to produce a finer adjustment.Moreover, the position of the return stop I24 lessens the efiect of thespring I25 on the return stop mechanism I24, I26, I36. Moreover, theangle of the contact between the bar I26 and the drum IIO allows acompensation for possible wear on the end of thebar I26.

In Figure 3 I have shown a drum 2I0 provided with shoes 2I2 and 2I4 botharranged to anchor through the shoe 2I4 upon the anchor 2I6 when brakingin a forward direction and through the shoe 2I2 on the anchor 2I6 whenbraking in a rearward direction. The anchor 2I6 is secured to thebacking plate 220 to which there is also secured the applying cylinder222. The shoes are returned from drum contact by means of springs suchas springs 225, only one being shown but any desired number beingprovided, Return stops 224 are provided with which levers such as 226,on opposite sides of the shoe, arc arranged to contact.

The levers 226 are pivoted as at 228 on the associated shoe and areprovided with lugs 229 arranged to contact with the drum when the brakeis being applied. The levers are formed with teeth 234 which cooperatewith pawls 236 and 231. A spring 239 is provided which tends to hold theteeth 234 in contact with one of the pawls 236 and 231 so as to preventundesired movement of the lever 226. By the provision of the two pawlsan adjustment is possible one-half as large as would be possible withonly one pawl. The lever 226 is provided with a guide slot 232 throughwhich there protrudes a bolt 233 secured to the associated shoe.

It will be seen that the lever 226 thus determines the return positionof the shoe and that as the lining wears the drum contacting with thelug 229 will move the lever 226 to adjust the return position of theshoe to maintain proper lining clearance.

In the arrangement shown in Figure 4 there is a drum 3I0 with whichthere are associated shoes 3I2 and 3M. These shoes are of the servo typeshown in Figure 3. Not only is means provided for adjusting the returnposition of the shoes so as to maintain a constant lining clearance, butalso means is provided to increase the effective length of the shoes sothat no adjustment of the applying means becomes necessary. Pivoted onthe primary shoe 3I2 is a lever 326 provided with a drum contact lug 329and arranged to contact in'returned position with a stop 324.

The lever 326 is provided with a pawl 336 which cooperates with a camsurface 334 formed on a bracket 335 secured as by welding to the shoe3I2. Pivoted on the lever 326 is an auxiliary lever 346 provided with 2.lug 342 and with an extension 344. The bracket 335 is provided also withteeth 346 arranged to cooperate with a pawl 348 pivoted on a lever 350.The lever 350 is pivoted as at 352 on the shoe 3I2 and normallypivotally contacts as at 354 with the shoe 3I4. The lever 356 isprovided with a lug 356 which cooperates with the extension 344 of thelever 340.

In normal brake application without wear of the lining the levers 326and 356 maintain the same position relative to the shoe 3I2. The lug 321of the lever 326 contacts the stop 324 to maintain the proper shoeclearance. The brak ing torque of the shoe 3I2 is transmitted throughthe lever 350 to the shoe 3I4 at 354 to apply the shoe 3I4. Both shoesanchor in one direction of braking through the shoe 3I4, and in theother direction of braking through the shoe 3I2 When the lining wearsthe lug 329 contacts with the drum before the lining 3I3 and thus movesthe lever 326 about its pivot relative to the shoe 3I2 and moves thepawl 336 relative to the cam surface 334. When the brake is released andthe shoe 3I2 returns the lug 342 contacts the stop 324 before the lug321 does and thus moves the auxiliary lever 340. This causes theextension 344 to contact the lug 356 and while the brake is beingreleased moves the lever 350 about its pivot causing the pawl 348 toride over one of the teeth 346 thus lengthening the connection betweenthe shoes 3I2 and 3I4 at 352 and 354.

In the brake shown in Figure 5 there is a drum 4I0 with which there areassociated brake shoes M2 and M4. Pivotally mounted on the shoe 2 is alever 426 having a drum contact lug 429 and aieaaac a stop contactingbase 421, the latter being a spring 138 looks the bar 128 againstmovement adapted to contact with the stop 424. The lever 426 also has alug 436 arranged to contact with the cam face of a rotatable cam 434.The-cam 434 is normally held in contact with the lug 436 by a spring 435which is also arranged to exert a pull on the cam 434 tending to rotateit in a clockwise direction.

As stated above, the cam is normally held in contact with the lug 436,but when due to lining wear the lever 426 moves into contact with thedrum prior to lining contact, the lever 426 is rotated counterclockwiseand the lug 436 moves away from the cam 434. Thereupon the cam 434 isrotated by the spring 435 to take up the clearance between the cam andthe lug. Thus the lever 426 is adjusted relative to the shoe 2 andconstant clearance is maintained. The lever 426 also has pivoted thereonan auxiliary lever 446 which is arranged to contact with an auxiliarystop- I and with an extension 456 formed on a lever 456. The lever 456is pivoted at 452 and pivotally abuts against the shoe 4 at 454. A earn446 mounted on a pivot 441 carried by an extension 445 of the web of theshoe H2 is normally urged into contact with the lever 456 by a spring448 and serves a function similar to that of the cam 434 in maintainingthe position of the lever 456 and in adjusting the lever 456 to extendthe connection between the shoes to compensate for lining wear. Thelever 456 has a pawl tooth 449 engaging ratchet teeth on the edge of cam446.

In the brake shown in Figure 6, the drum 5I6 is associated with shoes5I2 and 5, the shoe 5I2 having pivoted thereon levers 526, 546, 556. Thelever 526 is formed with a drum contacting lug 529, with a cam face 521adapted to contact with a stop 524 and with an extension 536. The lever546 is provided with a cam face 534 with which the extension 536contacts and with an extension 544 which is arranged to contact with thecam face 556 of the lever 556. The lever 556 also pivotally abutsagainst the shoe 5 as at 554.

In the arrangement shown in Figure '1, there is provided a drum 6I6having a pair of shoes, each of which is similar to the shoe l4. Thebacking plate 626 carries a pair of anchors such as the anchor 6I6. Inthe counterclockwise direction of rotation of the drum, both shoesanchor on one of theanchors BIG and in clockwise rotation of the drumboth shoes anchor on thecorresponding anchor on the opposite side of thebrake. The shoe 6 has pivoted thereon as at- 628 a lever 626 having adrum contact lug 629 and an anchor contact lug 623, which is formed witha guide slot 632 through which there extends a guide bolt 633. It isalso formed with teeth 634 with which pawls 636 and 631 are arranged tocooperate. Application of the brake when the opposite shoe is anchoredwill, if wear has occurred on the lining, shift the lever 626 to makethe desired adjustment.

In the arrangement shown in Figure 8 the drum H6 is arranged tocooperate with a pair of shoes 1 I4 and both of these shoes are arrangedto anchor on a single anchor "6 arranged betweentheir ends. A hydraulicwheel cylinder actuator 122 is arranged to spread the shoes apart toapply them to the drum. The righthand shoes 1| 4 is provided with guidelugs 128, 136, 13I and 132 between which a bar 126 is arranged to slide.The bar 126 is provided with a drum contact lug 129 and with an anchorreceiving recess "1. A friction pawl 136 provided with in one directionrelative to the shoe 1, but allows the bar to be moved by drum contact,when the shoe carrying it is the unanchored shoe. to effectivelylengthen the shoe when the lining has been worn. V

In the arrangement shown in Figure 9, the drum M6 is arranged tocooperate with shoes such as the shoe M2, the shoes being applied by awheel cylinder actuator 822 and being withdrawn from drum contact whenreleased by a spring 825. A cam 834 connected with the shoe 8l2 by aspring 835 is provided with an oversize hole 821 through which thereextends the pin 824 secured to the backing plate. In ordinaryapplication of the brake, the cam 834 is held in contact with the shoe8I2 by, the spring 835 and moves with the shoe. However, when. thelining becomes worn, the pin 824 contacts the inner side of the hole 821and the shoe is then moved away from the cam. Thereupon the spring 835rotates the cam to take up the slack and a constant drum clearance isthus maintained.

In the arrangement shown in Figure 10, the drum SM is associated with apair of shoes such as the shoe 9I2. Mounted on the shoe 9| 2 is a lever926 having a cam face 936 arranged to contact with a friction pawl 934also pivoted on the shoe 9I2. The lever 926 is formed with a slot 921within which is positioned a return stop 924. Application of the shoe M2to the drum normally carries with it the lever 926 and the returnposition of the shoe is determined by the contact of the stop 924 withthe slot 921. However, when the lining becomes worn, application of theshoe to the drum causes a movement of the lever 826 relative to the shoeby reason of the contact of the lug 924 with the opposite side of theslot and the position of the lever 926 is thus adjusted to maintainconstant drum clearance. The friction pawl 934 is moved by the spring935 to lock the lever 926 in its adjusted position.

In the arrangement shown in Figure 11 the drum I6I6 is provided withshoes such as the shoe I6I4 which are arranged to be applied by ahydraulic wheel cylinder actuator I622. The backing plate I626 isprovided with a pin I624 which extends through a slot I621 in a leverI626 which is formed with teeth I634 which cooperate with teeth I636formed on the web of the shoe I6I4. The lever I 626 is also connect'edtothe shoe I6I4 by a spring I639.

In the arrangement shown in Figure 12 the drum I I I6 is associated withshoes III2 and I I I4. This brake is of the servo type and both shoesare arranged to anchor on one or the other depending upon the directionof braking, the same as described for shoes 2I2 and 2I4 shown in Figure3. In forward braking in which, as shown, the drum is rotating in aclockwise direction. both shoes anchor through the shoe III2 on ananchor, not shown, but which may be the same as the anchor 2I6 in Figure3. associated with said shoe. The shoe III4 is moved into drum contactby any suitable conventional means, not shown, which may be a wheelcylinder such as the wheel cylinder 22 shown in Figure l.

The movement of the shoe III4 is transmitted to the shoe III2 to applythe shoe III2 to the drum and the anchoring torque of the shoe III4 isabsorbed by this transmission and in part is transmitted through theshoe II I2 to the anchor. I have provided means for transmitting part ofthe anchoring torque of the shoe II I4 to the shoe III2 and forconverting and utilizing this part of this force as applying force forthe shoe IH2, the connection between the shoes being so arranged as toabsorb part of the force and transmit the same directly to the backingplate and thereby reduce the force acting on the shoe II I2 so that thebraking action of the two shoes may be more nearly uniform. Secured tothe backing plate I I29 is a pin H60 on which there is pivoted anS-shaped lever H62. The lever H62 has a. shoe contact portion H64arranged to contact with an extension H66 formed on the end of the shoeIII4 and is also formed with a shoe contact portion I I68 facing in theopposite direction from the contact portion H64 and arranged to contactwith an extension H10 formed on the shoe HI2.

Pivoted on the lever H62 as at H12 is an auxiliary S-shaped lever H14formed with a shoe contact portion H16 with which an extension H18formed on the shoe III2 is arranged to contact and also formed with ashoe contact portion H80 facing in the opposite direction from thecontact portion H16 and with which an extension H82 formed on the shoeIH4 is arranged to contact. The lower end of the auxiliary lever I I80is formed with a lug H84 which is arranged at times to contact with theright band edge of the extension H82 hook-shaped.

Mounted on the lever I I62 at its upper end is a cam H34 having teethH46 arranged to contact with the pointed upper end H36 of the auxiliarylever H14. A spring H48 connects the cam H34 with the auxiliary leverH14. During normal brake application in the forward direction the shoeIH4 is applied to the drum and rotation of the drum moves the shoe IH4in a clockwise direction. The extension H16 acting on the portion H64 ofthe lever H62 causes that lever to pivot on the pin H60 and the portionH68 contacts with the extension H10 to move the shoe III2 to drumcontact. Due to the arrangement of the lever, the shoe movement of theshoe I I I2 is greater than the movement of the shoe II I4 and theapplying force is less than the force exerted by the shoe III 4, theremainder of the thrust fromthe shoe-IH4 being transmitted through thepin I I60 to the backing plate.

Normally the lever H14 and the cam H34 move as a unit with the leverH62. In this movement a slight clearance between the lug H84 and theextension H82 is not completely taken up. If, however, due to wear ofthe lining this clearance is taken up, the lug H84 will contact withextension H82 and will retard the movement of the auxiliary lever H14,thus moving the point H36 out of contact with the teeth H46 andthereupon the spring H48 will rotate the cam H34 and adjust the lengthof the connection between the two shoes so as to compensate for liningwear. In reverse braking, the shoe HI2 anchors at H16 on the lever H14,and the lower end of lever H14 transmits part of the force from shoe I II2 to the shoe I I I4 as an applying force. The remainder of theanchoring thrust from the shoe III2 is transmitted from the lever II 14through the pivot H12 and the point of engagement with the cam H34 tothe lever H62, and thence through the pivot H60 to the backing plate.The two levers H62 and H14, as they are swung relatively to each otherwhen adjustment takes place as described above, in effect form a singlelever whose width increases as successive adjustments are made.

In the arrangement shown in Figure 13 the drum I2I0 is associated withshoes I2I2 and I2I4 which are of the servo type similar to that shown inFigure 12. Mounted on the backing plate I 220 by means of a pin I260 isa lever I262 formed with slots I264 and I268. Slotted pins I266 and I210are associated with the slots I264 and I268 respectively. The pins I 266and I210 are formed with slots at each end and the opposite slotted endsfrom those associated with the lever I262 are associated respectivelywith slots I261 and I21I formed respectively in the shoes I2I4 and I2I2.

Pivoted at I212 on the lever I262 is an auxiliary lever I214 formed withslots I 216 and I280 which are associated with slotted pins I218 andI282 respectively. The opposite slotted ends of the pins I218 and I282fit over respectively slots H19 and I283 formed in the shoes I2I2 andI2I4 respectively. The lever I262 is connected with the shoe I2I2 by aspring I248 and with the shoe I2I4 by a spring I249. Pivoted on the pinI260 is a toothed cam I234 which is arranged to be adjusted manuallyfrom the outside of the backing plate.

In forward braking, shoe I2I4 swings lever I262 to the left, part of itsanchoring force acting as an applying force through lever I262 on shoeI2I2, and the remainder being transmitted to the backing plate throughthe pivot I260. In reverse brakingv the shoe I2I2 swings lever I214 (andwith it the lever I262) to the right, part of its anchoring force beingutilized as an applying force acting at I283 on the shoe I2I4 and theremainder being transmitted to the backing plate. Adjusting the cam I234in efiect increases the width of the connection consisting of the leversI214 and I262, which act as a unit in the normal operation of the brake.

In the arrangement shown in Figure 14, the drum I3I0 is associated withshoes I3I2 and I3I4 in a type of brake similar in most respects to thatshown in Figure 12. The lever I362 pivoted on the pin I360 and theauxiliary lever I314 pivoted at I312 on the lever I362 correspondessentially to the S-shaped levers shown in Figure 12. The cam I334connected to the lever I314 by the spring I348 corresponds essentiallyto the cam H34. However, no lug similar to the lug H84 is provided but Ihave provided different means for automatically adjusting the connectionbetween the two shoes to take up clearance due to lining wear.

Mounted on the shoe I3I4 as at I386 is a supporting link I388 whichcarries a pin I390 extending through a slot I392 in a link I394 and thussupports the link at one end. The opposite end of the link I394 ispivotally connected as at I396 to the auxiliary I384. A spring I391connected to the link I394 and to the shoe I3I4 normally maintains thelink I394 in the position shown. The outer end of the link I394 isformed with a drum contact surface I329 so that when the shoe is movedinto drum contact this portion I329 approaches the drum.

When the lining becomes worn the portion I329 contacts with the drum andwhen the lining is Worn sufficiently and the drum is rotating in aclockwise (forward) direction moved to the left as shown in Figure 14and thus moves the auxiliary lever I314 about its pivot I312 and allowsthe cam I334 to be adjusted by the spring I I348, thus adjusting theconnection between the shoes and taking up the clearance for liningwear. A spring I398 connects the shoe I3I4 to the lever I362 to aid incentering the shoes when the brake is released.

It is to be understood that the above-described embodiments of myinvention are for the purpose of illustration only and various changesmay be made therein without departing from the spirit and scope of myinvention.

I claim:

1. A brake comprising, in combination, a brake drum, an anchor, a brakefriction member having said anchor arranged at one end thereof, anchormeans mounted on said friction member and having a part arranged tocontact with said drum and having another part shifted lengthwise of theshoe by the pressure of the drum on the first part to compensate forwear of the brake and which is arranged to transmit the braking torqueof the friction member to said anchor, and means for releasably holdingsaid means in adjusted position relative to the friction member.

2. A brake as defined by claim 1, in which said friction membercomprises two shoes, one of which anchors on said anchor through saidanchor means when the drum is turning in one direction and the other ofwhich anchors directly on said anchor when the drum is turning in theother direction.

3. A brake comprising, in combination, a drum, a pair of shoesassociated therewith and arranged to anchor upon one shoe in onedirection of rotation and upon the other shoe in the opposite directionof rotation, a backing plate, a lever pivoted on said backing plate andhaving a thrust connection with both shoes and arranged to transferforce from one shoe to the other in one direction of rotation, and anauxiliary lever pivoted on the first named lever and having separatethrust connections with both shoes and arranged to cooperate with thefirst named lever to transfer force from the second named shoe to thefirst named shoe in the opposite direction of rotation.

4. A brake comprising, in combination, a drum, a pair of shoesassociated therewith and arranged to anchor upon one shoe in onedirection of rotation and upon the other shoe in the opposite directionof rotation, a backing plate, a member mounted on said backing plate andhaving a thrust connection with both shoes and arranged to transferforce from one shoe to the other in one direction of rotation, anauxiliary member associated with the first named member and havingseparate thrust connections with both shoes and arranged to cooperatewith the first named member to transfer force from the second named shoeto the first named shoe in the opposite direction of rotation, and meansfor adjustably connecting said members.

5. A brake comprising, in combination, a drum, a pair of shoesassociated therewith and arranged to anchor upon one shoe in onedirection of rotation and upon the other shoe in the opposite directionof rotation, a backing plate, a lever pivoted on said backing plate andhaving a thrust connection with both shoes and arranged to transferforce from one shoe to the other in one direction of rotation, anauxiliary lever pivoted on the first named lever and having separatethrust connections with both shoes and arranged to cooperate with thefirst named lever to transfer force from the second named shoe to thefirst named shoe in the opposite direction of rotation, and means forangularly adjusting the levers relatively to each other.

6. A brake comprising, in combination, a drum, a pair of shoesassociated therewith and arranged to anchor upon one shoe in onedirection of rotation and upon the other shoe in the opposite directionof rotation, a backing plate, a lever piva pair of shoes associatedtherewith and arranged to anchor upon one shoe in one direction ofrotation and upon the other shoe in the opposite direction of rotation,a backing plate, a lever pivoted on said backing plate and arranged totransfer force from one shoe to the other in one direction of rotation,an auxiliary lever pivoted on the first named lever and arranged tocooperate with the first named lever to transfer force from the secondnamed shoe to the first named shoe in the opposite direction ofrotation, and means operated automatically in accordance with liningwear for adjusting said levers relatively to each other, said meansbeing ineffective to adjust the position of the levers for clearance dueto expansion of the drum.

8. A brake comprising, in combination, a drum, a primary shoe and asecondary shoe associated therewith and arranged to anchor upon thesecondary shoe in one direction of rotation and upon the primary shoe inthe opposite direction of rotation, a backing plate, a lever pivoted onsaid backing plate and having a thrust connection with both shoes andarranged to transfer force from the primary shoe to the secondary shoein one direction of rotation and an auxiliary lever pivoted on the firstnamed lever and having separate thrust connections with both shoes andarranged to cooperate with the first named lever to transfer force fromthe secondary shoe to the primary shoe in the opposite direction ofrotation.

9. For a brake an adjusting device comprising a cam wheel mounted on apivot, a member movable relative to said pivot and contacting the camsurface of said wheel, a spring connected at one end to said movablemember and at the other end to said cam wheel and passing intermediateits ends around said pivot whereby the spring tends to rotate said camwheel about said pivot, but normally by reason of the contact with saidcam wheel, said movable member prevents rotation of said'cam wheel.

10. For use in a brake an adjusting device comprising a cam wheel formedwith a toothed cam surface and mounted on a pivot, a member movablerelative to said pivot and having a tooth co-' operating portioncontacting the toothed cam surface of said wheel, a spring connected atone end to said movable member and at the other end to said cam wheeland passing intermediate its ends around said pivot whereby the springtends to rotate said cam wheel about said pivot but normally the contactbetween said cam wheel toothed surface and movable member preventsrotation of said cam wheel.

11. A brake comprising a drum and a pair of shoes, a lever deviceadjustably connecting the shoes and movable to expand the shoes to takeup for wear, and a lever mounted on one of the shoes and which isengageable with the drum and is shifted by the drum in case of wear andwhich is provided with means interengaging with said lever device tooperate it.

12. A brake comprising a drum and a pair of shoes, a lever pivoted onone shoe and engaging shoes, a lever device connecting the shoesandwhich is operable to expand the shoes to take up for wear, and amember mounted on one shoe and which is shiftable relatively to saidshoe in case of wear by direct engagement with the drum and which hasmeans for so operating the lever device when it is shifted relatively toits shoe.

14. A brake comprising a drum and a pair of shoes, a lever deviceconnecting the shoes and which includes two levers mounted on a pivotand a cam connecting the levers and which cam is operable to expand theshoes to take up for wear, and a member mounted on one shoe and which isshiftable relatively to said shoe in case of wear by direct engagementwith the drum and which has means for causing operation of the cam andso operating the lever device to adjust the brake when said member isshifted relatively to its shoe.

15. A brake comprising a drum and a pair of shoes, a lever deviceconnecting the shoes and which is operable to expand the shoes to takeup for wear, and a member mounted on one shoe and which is shiftablerelatively to said shoe in case of wear by direct engagement with thedrum and which has means for so operating the lever device when it isshifted relatively to its shoe, said device comprising a lever pivotedon one shoe and engaging the other shoe.

ber to compensate for wear of the shoe.

17. A shoe for use in a brake having mounted thereon wear-compensatingmeans including a member shiftable by direct engagement with a brakedrum engaged by the shoe together with a lever pivoted on the shoe, andmeans operated by said member to move the lever angularly on the s 0e.

18. A shoe for use in a brake having mounted thereon wear-compensatingmeans including a member shiftable by direct engagement with a brakedrum engaged by the shoe together with a lever pivoted on the shoe and acam device operated by said member to move the lever angularly on theshoe.

19. A brake comprising shoes, a drum, means for adjusting for wear whichis shiftable to increase the effective length of the shoes and whichincludes a part directly engageable with the drum and through which thedrum operates said means, a pivoted member movable to maintain saidmeans in adjusted position without preventing further adjustment, and aspring connected to the pivoted member and urging it in a direction tomaintain the adjusted position.

WILLIAM J. RYAN.

